δ阿片受体激动剂对NGl08—15细胞延迟整流钾通道的双向调节作用

目的 观察δ阿片受体激动剂DPDPE对NGl08—15细胞膜上延迟整流钾通道的调节作用。方法 将NGl08—15细胞膜电位钳制在—90mV,给予时程为150ms的阶跃脉冲刺激,由—50mV逐渐增至 80mV,每次递增10mV,记录到一系列外向延迟整流钾电流,记录给予不同浓度S阿片受体激动剂DPDPE前后的钾电流变化,比较其作用与给药浓度的关系,同时观察阿片受体拮抗剂纳洛酮(NAL)和特异性δ阿片受体拮抗剂纳曲酮(NTI)对δ阿片受体激动剂DPDPE的阻断效应。结果 δ阿片受体激动剂DPDPE在高浓度(≥10^-6mo1/L)时,对钾通道产生兴奋性作用;而低浓度(≤10^-7mol/L)时,对延迟整流钾通道产生抑制作用,且作用均随着时间的延长而逐渐增强。结论 δ阿片受体激动剂DPDPE对延迟整流钾通道的作用具有双向调节作用。

Dual regulation by delta opioid receptor agonists on the delayed rectified potassium channels in NG108-15 cells

OBJECTIVE: To investigate the dual effects by the delta opioid receptor agonists DPDPE on the delayed rectified potassium channels in NG108-15 cells. METHODS: A series of outward currents were evoked in NG108-15 cells by depolarizing voltage from -50 mV to +80 mV at holding potential of -90 mV. These currents were delayed rectified potassium currents. Relatively selected delta opioid receptor agonists DPDPE of higher and lower concentrations were used to modulate the delayed rectified K+ current in NG108-15 cells. Opioid receptor antagonist Naloxone (NAL) and relatively selected delta opioid receptor antagonist Naltrindole (NTI) were used in the present experiments for the characterization of the actions of opioid receptors. RESULTS: The relatively higher concentrations of delta opioid receptor agonist DPDPE (> or = 10(-6) mol/L) significantly increased the amplitude of the delayed rectified K+ current. On the contrary, the relatively lower concentrations of DPDPE (< or = 10(-12) mol/L) decreased the amplitude of the delayed rectified K+ current (P < 0.05). Furthermore both the increase and decrease were time-dependent. CONCLUSIONS: delta opioid receptor agonist has dual regulatory effects on the delayed rectified potassium channels in NG108-15 cells.